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NFF

National Flood Frequency program

Version History

Version 3.2 - 2004/12/14 - Updated the database to NFFv3.2_2004-12-14.mdb. Added new peak-flow equations for Connecticut and Kentucky. Corrected an error in the units displayed for conveyance in the Houston urban equations from in/hr to cubic feet per second. Corrected an error in the Wisconsin Area 1 equation for the 5-year recurrence interval.

Version 3.2 - 2004/09/29 - Updated the database to NFFv3.2_2004-09-29.mdb. This database contains new peak-flow equations for Alaska, Idaho, Ohio, Tennessee, Vermont, Wisconsin, and Wyoming. Along with the new database comes the ability to display 90-percent prediction intervals with the estimates for some of the updated States.

Version 3.2 – 2003/04/30 - Fixed a bug in the weighting routine that occurred when equivalent years of record were missing for the regression estimates, and a bug that occurred when the drainage area for an ungaged site was in more than one region and the regions had different sets of return intervals.

Version 3.1.1 - 2003/03/28 - Fixed a bug in the weighting routine that was introduced in the version 3.1 update.

Version 3.1 - 2003/02/27 - Fixed a problem with solving the national urban equations that occurred when one or more of the local rural equations were missing for the region of interest. If a rural equation, such as the 5-year flow, was missing NFF would use the flow estimate for the next available recurrence interval, such as the 10-year flow, to estimate the urban flow for the missing recurrence interval. All estimates for higher recurrence intervals would also be incorrect.

Version 3.0 - 2002/10/15 - Major change in converting user interface from Microsoft DOS to Microsoft Windows and converting data base from a binary file to Microsoft Access (Note: Use of trade or product names is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey). Updates or corrections to equations for

• Alabama
• Alaska
• American Samoa
• Arizona
• Arkansas
• Colorado
• Delaware
• Georgia - rural and urban
• Hawaii
• Idaho
• Iowa
• Kansas
• Kentucky - Jefferson w:st="on">County urban
• Louisiana
• Maine
• Maryland
• Minnesota
• Missouri
• Nebraska
• Nevada
• New Mexico
• North Carolina - rural and urban
• Oklahoma
• Pennsylvania
• Puerto Rico
• South Carolina - rural and urban
• South Dakota
• Texas - rural
• Utah
• Virginia
• Washington
• West Virginia

Version 2.0 - 1996/09/15 - A non-USGS release that added conversions between English and metric units.

Version 1.4 - 1996/09/30 - NFF data base updated to amend incorrect values for:

• New Jersey--the constant 1 was removed from being added to the actual value entered for impervious cover, I
• New York--incorrect exponents and an incorrect regression constant were corrected for Region 6's 25-year and 500-year equations, respectively
• Wisconsin--the constant -2.3 was added to the data base to be applied automatically to the actual value entered for 2-year 24-hour rainfall, INTENS, for Areas 1, 3, and 5; incorrect exponents were corrected for Area 3's 5-, 25-, 50-, and 100-year equations

Version 1.3 - 1996/02/14 - Corrected labeling of flood-frequency recurrence intervals for North Dakota. The equations developed for North Dakota are for the 2-, 10-, 15-, 25-, 50-, 100-, and 500-year recurrence intervals rather than the standard 2-, 5-, 10-, 25-, 50-, 100-, and 500-year intervals.

Version 1.2 - 1995/06/02 - NFF data base updated to amend incorrect exponents in West Virginia's Region 6 equations for the 2-year and 10-year recurrence interval.

Version 1.1 - 1994/11/21 - Initial release.